Database backup systems require sufficient storage space for the database and the backups of partitions of the database. As databases get larger over time, storage space requirements for the backups may become exponentially larger when multiple backups are kept for various points-in-time. Taking full backups of a partition in the database in response to small changes to data of the partition results in using more storage space compared to the change in storage requirements due to the small changes.
Differential-based backup systems reduce the overall storage requirements by storing only the differences relative to a reference point, such as a snapshot. Over time, requests for point-in-time restoration of data becomes more costly or inefficient due to applying the differences to the reference point over longer periods of time. Change logs also have a cost associated when storing the change logs at a storage service. Over time, the change logs may cost more than they are worth in terms of utility. Performing operations, such as size calculations, on the change logs in an iterative manner may not be cost effective or computationally efficient.
While embodiments are described herein by way of example for several embodiments and illustrative drawings, those skilled in the art will recognize that embodiments are not limited to the embodiments or drawings described. It should be understood, that the drawings and detailed description thereto are not intended to limit embodiments to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to. When used in the claims, the term “or” is used as an inclusive or and not as an exclusive or. For example, the phrase “at least one of x, y, or z” means any one of x, y, and z, as well as any combination thereof.